impetus

noun

im·​pe·​tus ˈim-pə-təs 

1

a

: a driving force : impulse

The push serves as the impetus, the child and the swing reach the highest point on their own, and then gravity returns the child and swing to the starting place.

—Natalie Willman Duffy

People were short on impetus to spend big as well, relatively speaking.

—George Nelson

b

: the effect of a driving force

It was a difficult catch. … Bob got to it with one hand, and held it. His impetus carried him on almost to where Burgess was standing.

—P. G. Wodehouse

2

a

: incentive, stimulus

felt no impetus to do well at school

Introducing our son to Asia was a major impetus for our trip.

—Ariel Frager

b

: stimulation or encouragement resulting in increased activity

Their discoveries have given impetus to further research.

… the impetus for the retreats … is the root of why Owens started the podcast to begin with.

—Deborah Vankin

3

: the property possessed by a moving body by virtue of its mass and its motion

—used of bodies moving suddenly or violently to indicate the origin and intensity of the motion

Did you know?

Impetus Has Latin Roots

Impetus provides the “why” for something: it can be understood as a driving force (as when winning a competition is the impetus for training), an incentive (as when increased skills serve as an impetus for taking a class), or encouragement (as when difficulties are the impetus for improvements). But its root packs more of a wallop: Latin impetus means “assault” as well as “impetus,” and it comes from impetere meaning “to attack.” (Impetere itself comes from petere, meaning “to go to, seek.”) If these origins seem a tad aggressive for such a genteel-sounding word as impetus, consider phrases and idioms like light a fire under someone and push comes to shove, both used when a strong impetus is provided for someone to act, decide, or accomplish something.

Synonyms of impetus

• incentive
• encouragement
• motivation
• stimulus

Examples of impetus in a Sentence

In a revealing comment, Mr. Updike says an impetus for Rabbit, Run was the "threatening" success of Jack Kerouac's On the Road, the signature book of the 1950s Beat Generation, and its frenetic search for sensation. —Dennis Farney, Wall Street Journal, 16 Sept. 1992

But 1939 gave new impetus to the Western with the Cecil B. de Mille railway epic Union Pacific, John Ford's skillful and dramatic Stagecoach,  … and George Marshall's classic comic Western, Destry Rides Again. —Ira Konigsberg, The Complete Film Dictionary, 1987

… new techniques of navigation and shipbuilding enlarged trade and the geographical horizon; newly centralized power absorbed from the declining medieval communes was at the disposal of the monarchies and the growing nationalism of the past century gave it impetus … —Barbara W. Tuchman, The March of Folly, 1984

His discoveries have given impetus to further research.

the reward money should be sufficient impetus for someone to come forward with information about the robbery

Recent Examples on the Web

That recognition of the need for a multi-lateral approach to global health was the impetus behind creating the WHO in the first place, based on the reality that countries interact and depend on one another—and the health of one affects the health of all. —Alice Park, Time, 22 Jan. 2026

The attack created an impetus to justify the settlement, the local settlement council chair, Yaron Rosenthal, told AP. —Julia Frankel, Los Angeles Times, 20 Jan. 2026

What was the impetus behind having Sam as the first nonbinary headliner at a festival that is so famous for following in the tradition of Lilith Fair’s female lineups? —Chris Willman, Variety, 20 Jan. 2026

The real impetus, though, may be simple pride. —Eric Lutz, Vanity Fair, 20 Jan. 2026

Word History

Etymology

Latin, assault, impetus, from impetere to attack, from in- + petere to go to, seek — more at feather

First Known Use

1641, in the meaning defined at sense 1a(1)

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Kids Definition

impetus

noun

im·​pe·​tus ˈim-pət-əs 

1

a

: a driving force : impulse

b

: incentive

2

: momentum sense 1